Leptospirosis in Equine Fetuses, Stillborn Foals, and Placentas

Abstract

Abstract. Leptospirosis was diagnosed in 5 1 equine fetuses and 16 stillborn foals with gestational ages from 3% to 11 months. Diagnosis was based on one or more of the following: positive fetal antibody titer, positive fluorescent antibody test, demonstration of spirochetes in kidney and/or placental sections stained by the Warthin-Starry technique, high leptospiral titers in aborting mares, or isolation of Leptospira spp. from fetal organs. Gross lesions were observed in 80.3% of the fetuses, stillborn foals, and placentas. Gross placental lesions included nodular cystic allantoic masses, edema, areas of necrosis of the chorion, and necrotic mucoid exudate coating the chorion. The liver (23 cases) was enlarged, mottled, and pale to yellow. The kidneys (seven cases) were swollen and edematous with pale white radiating streaks in cortex and medulla. Microscopic lesions were observed in 96% of fetuses, stillborn foals, and placentas. Placental lesions consisted of thrombosis, vasculitis, mixed inflammatory cell infiltration of the stroma and villi, cystic adenomatous hyperplasia of allantoic epithelium, and villous necrosis and calcification. Fetal lesions included hepatocellular dissociation, mixed leukocytic infiltration of the portal triads, giant cell hepatopathy, suppurative and nonsuppurative nephritis, pulmonary hemorrhages, pneumonia, and myocarditis. Spirochetes were demonstrated with the Warthin-Starry stain in the allantochorion and/or kidney of 69 of the 7 1 cases. Using the direct fluorescent antibody technique, 56/60 cases tested positively for leptospires. Leptospires were isolated from fetal tissues in 20/42 cases. Sixteen of the isolates were identified by restriction enzyme analysis as Leptospira interrogans serogroup Pomona serovar kennewicki; case Nos. 36 and 41 were serovar grippotyphosa. The other two isolates were not identified.Microagglutination titers against leptospires were demonstrated in the body fluid of 47/67 cases tested and titers ranged from 1 : 50 to greater than 1 : 1,638,400 against Leptospira interrogans serovars pomona, grippotyphosa, copenhageni, hardjo, canicola, and bratislava. Sixty-two of 7 1 aborting mares tested had titers ranging from 200 to greater than 3,276,800. Leptospiral antibody titers in the body fluid and gross and histopathologic lesions did not differ with age, breed, or sex or between fetuses and stillborn foals.

A study of leptospirosis in South African horses and associated risk factors

“…Immunofluorescence (IF) was found to be very useful in the demonstration of leptospires in tissue samples (Ellis et al 1983, Poonacha et al 1993. Immunohistochemistry (IHC) can demonstrate the distribution and localization of antigen in tissue sections (Szeredi and Haake.…”

Cloning and Molecular Characterization of an Immunogenic LigA Protein of Leptospira interrogans

“…Infection is acquired either directly or indirectly from infected animals. In horses, the most common manifestations of infection are abortion and uveitis (29). L. interrogans serovar pomona type kennewicki is the predominant serovar isolated from aborted equine fetuses, whereas L. interrogans serovar grippotyphosa is found less frequently (7)(8)(9).…”

Molecular Detection of Leptospira Kirschneri in Tissues of a Prematurely Born Foal

“…1,[3][4][5][6]8,9,12,15 This disease should always be included as a differential diagnosis for equine abortion cases. However, in the absence of prominent gross and microscopic lesions, 12 the significance of an infection with Leptospira is unclear. Detection of Leptospira spirochetes or their antigen by silver staining is difficult and nonspecific.…”